Error on using nullsafe property access on empty array

[hollodotme]

Hi, before opening an issue, I wanted to check opinions on the following error.

<?php declare(strict_types = 1);

/** @var array<stdClass> $array */
$array = [];

echo $array[0]?->maybeNotThere ?? 'else this';

/** @var array<stdClass|null> $array */
$array = [];

echo $array[0]?->maybeNotThere ?? 'else this';

See: https://phpstan.org/r/a203fb57-a5f8-48df-b652-1cfcd01b0607

This code emits

Line	Error
6	Using nullsafe property access on non-nullable type stdClass. Use -> instead.

I thought the nullsafe property access is intended to be used like the nullsafe operator ?? when it comes to array access.

The second array declaration array<stdClass|null> is actually not correct, because the array should contain only stdClass objects, not null values, but it can be empty for sure.

If the array is empty, an access like $array[0]->something leads to a null evaluation of $array[0] and will raise a runtime error of property access on non-object. So using $array[0]?->something ?? 'else' is the way to avoid the latter and provide a fallback value.

TL;DR
I think this error should not be emitted in this case, because the array access always can lead to a null evaluation, if the array is empty or if a non-existing index is accessed.

What do you think?

[ondrejmirtes]

Consider this: https://3v4l.org/WB2UW You're getting a warning for accessing an undefined array key. The ?-> operator should only save you from getting "calling method on null": https://3v4l.org/Bsuoc (still getting a warning)

It's a bit messy because you're not getting the warning thanks to ?? operator afterwards: https://3v4l.org/jdNaC

I'd say that in this situation, code that uses just -> works identically: https://3v4l.org/paRS1

So PHPStan's error "Using nullsafe property access on non-nullable type stdClass. Use -> instead." is actually correct I'd say. WDYT?

[hollodotme]

Ah, you're right, I somehow missed that this works as well:

<?php declare(strict_types = 1);

/** @var array<stdClass> $array */
$array = [];

echo $array[0]->maybeNotThere ?? 'else this';

Thanks.